AT_BISON_CHECK([[-Werror,none,yacc input.y]], [[1]], [[]], [[stderr]])
AT_CHECK([[sed 's/^.*bison:/bison:/' stderr]], [[0]],
[[bison: warnings being treated as errors
-input.y:2.1-7: error: POSIX Yacc forbids dashes in symbol names: foo-bar [-Werror=yacc]
+input.y:2.1-7: warning: POSIX Yacc forbids dashes in symbol names: foo-bar [-Wyacc]
]])
[mv stderr experr]
AT_BISON_CHECK([[-Werror,no-all,yacc input.y]], [[1]], [[]], [[experr]])